1. Field of the Invention
The present invention relates to downhole apparatus permitting separation of one part of downhole equipment from another part thereof.
2. The Prior Art
It is not uncommon for a drill bit to become stuck inhole during downhole oil and gas drilling operations. In order to allow retrieval of a downhole drill string when a drill bit becomes jammed, it is known to provide a drill string with an emergency release joint immediately uphole of the drill bit. During normal operation, the release joint transmits torque from a motor to the drill bit. However, in the event that the drill bit becomes jammed to the extent that axial and rotational movement of the drill bit is not possible, the drill bit may be separated from the remainder of the drill string by virtue of the release joint. The remainder of the drill string may then be moved axially uphole so that specialist retrieving equipment may be run to the drill bit in a fishing operation.
Although the prior art release joints are effective in providing a mechanism for releasing the drill bit from the remainder of the drill string, the prior art devices are unduly complicated in design.
It is an object of the present invention to provide apparatus allowing the release of one part of equipment from another part thereof, wherein said apparatus is of a relatively simple design and relatively inexpensive to manufacture.